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rcu/tree: Make debug_objects logic independent of rcu_head

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kfree_rcu()'s debug_objects logic uses the address of the object's
embedded rcu_head to queue/unqueue. Instead of this, make use of the
object's address itself as preparation for future headless kfree_rcu()
support.

Reviewed-by: Uladzislau Rezki <urezki@gmail.com>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Joel Fernandes (Google) 2020-05-25 23:47:48 +02:00 committed by Paul E. McKenney
parent 594aa5975b
commit 446044eb9c
1 changed files with 13 additions and 16 deletions
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29
kernel/rcu/tree.c
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@ -2970,13 +2970,11 @@ EXPORT_SYMBOL_GPL(call_rcu);
* @nr_records: Number of active pointers in the array
* @records: Array of the kfree_rcu() pointers
* @next: Next bulk object in the block chain
* @head_free_debug: For debug, when CONFIG_DEBUG_OBJECTS_RCU_HEAD is set
*/
struct kfree_rcu_bulk_data {
unsigned long nr_records;
void *records[KFREE_BULK_MAX_ENTR];
struct kfree_rcu_bulk_data *next;
struct rcu_head *head_free_debug;
};
/**
@ -3026,11 +3024,13 @@ struct kfree_rcu_cpu {
static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc);
static __always_inline void
debug_rcu_head_unqueue_bulk(struct rcu_head *head)
debug_rcu_bhead_unqueue(struct kfree_rcu_bulk_data *bhead)
{
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
for (; head; head = head->next)
debug_rcu_head_unqueue(head);
int i;
for (i = 0; i < bhead->nr_records; i++)
debug_rcu_head_unqueue((struct rcu_head *)(bhead->records[i]));
#endif
}
@ -3060,7 +3060,7 @@ static void kfree_rcu_work(struct work_struct *work)
for (; bhead; bhead = bnext) {
bnext = bhead->next;
debug_rcu_head_unqueue_bulk(bhead->head_free_debug);
debug_rcu_bhead_unqueue(bhead);
rcu_lock_acquire(&rcu_callback_map);
trace_rcu_invoke_kfree_bulk_callback(rcu_state.name,
@ -3082,14 +3082,15 @@ static void kfree_rcu_work(struct work_struct *work)
*/
for (; head; head = next) {
unsigned long offset = (unsigned long)head->func;
void *ptr = (void *)head - offset;
next = head->next;
debug_rcu_head_unqueue(head);
debug_rcu_head_unqueue((struct rcu_head *)ptr);
rcu_lock_acquire(&rcu_callback_map);
trace_rcu_invoke_kfree_callback(rcu_state.name, head, offset);
if (!WARN_ON_ONCE(!__is_kfree_rcu_offset(offset)))
kfree((void *)head - offset);
kfree(ptr);
rcu_lock_release(&rcu_callback_map);
cond_resched_tasks_rcu_qs();
@ -3228,18 +3229,11 @@ kfree_call_rcu_add_ptr_to_bulk(struct kfree_rcu_cpu *krcp,
/* Initialize the new block. */
bnode->nr_records = 0;
bnode->next = krcp->bhead;
bnode->head_free_debug = NULL;
/* Attach it to the head. */
krcp->bhead = bnode;
}
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
head->func = func;
head->next = krcp->bhead->head_free_debug;
krcp->bhead->head_free_debug = head;
#endif
/* Finally insert. */
krcp->bhead->records[krcp->bhead->nr_records++] =
(void *) head - (unsigned long) func;
@ -3263,14 +3257,17 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
{
unsigned long flags;
struct kfree_rcu_cpu *krcp;
void *ptr;
local_irq_save(flags); // For safely calling this_cpu_ptr().
krcp = this_cpu_ptr(&krc);
if (krcp->initialized)
raw_spin_lock(&krcp->lock);
ptr = (void *)head - (unsigned long)func;
// Queue the object but don't yet schedule the batch.
if (debug_rcu_head_queue(head)) {
if (debug_rcu_head_queue(ptr)) {
// Probable double kfree_rcu(), just leak.
WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
__func__, head);